1. Field of the Invention
The present invention relates generally to the packaging of electronic components. More particularly, the present invention;relates to a method for fabricating an electronic component package.
2. Description of the Related Art
Image sensors are well known to those of skill in the art. An image sensor included an active area, which was responsive to electromagnetic radiation. The image sensor was incorporated into an image sensor package, which protected the image sensor from dust and moisture.
In one image sensor package, the image sensor was located within an enclosure, which included a window. Electromagnetic radiation passed through the window and struck the active area of the image sensor, which responded to the electromagnetic radiation. The enclosure also served to protect the image sensor from dust and moisture. Although the enclosure around the image sensor was reliable and effective, fabrication of the enclosure was relatively complex, time-consuming, and thus expensive.
In accordance with one embodiment of the present invention, a method of forming an image sensor package includes coupling an image sensor, i.e., an electronic component, to a substrate. Bond pads of the image sensor are electrically coupled to interior traces on the substrate with bond wires. A first optically curable material is applied to enclose the bond wires. A second optically curable material is applied between a lid and the substrate. The first and second optically curable materials are cured with a first electromagnetic radiation such as ultraviolet radiation. The substrate, lid, and cured second optically curable material form a low cost enclosure around the image sensor.
In one embodiment, the first and second optically curable materials are optically entirely curable materials. In accordance with this embodiment, the first and second optically curable materials are cured immediately as a result of being irradiated with the first electromagnetic radiation. More particularly, the first and second optically curable materials are entirely cured while being irradiated with the first at electromagnetic radiation.
In an alternative embodiment, the first and second optically curable materials are optically activated materials. In accordance with this embodiment, the first and second optically curable materials cure over a period of time as a result of being irradiated with the first electromagnetic radiation. More particularly, the first and second optically curable materials cure initiate while being irradiated with the first electromagnetic radiation and then entirely cure over a period of time without further irradiation.
In one embodiment, after being cure initiated, the first and second optically curable materials entirely cure at room temperature, i.e., without heating. Alternatively, after being cure initiated, the first and second optically curable materials entirely cure at elevated temperature, e.g., are heated to reduce the curing time.
Advantageously, the first and second optically curable materials are cured rapidly, e.g., in a matter of seconds. This is in stark contrast to conventional thermally curable materials, which often had a cure time of several hours. By curing the first and second optically curable materials rapidly, the time required to fabricate the image sensor package is minimized. This, in turn, minimizes the fabrication cost of the image sensor package.
In one embodiment, the first and second optically curable materials are cured without heating the image sensor package to any appreciable extent. This is in stark contrast to conventional thermally curable materials, which required heating for several hours.
Accordingly, use of the first and second optically curable materials is well suited for applications in which it is important to keep the image sensor and any other temperature sensitive components of the image sensor package at low temperature, for example, to prevent degradation or damage to any color filters and/or other temperature sensitive materials of the image sensor.
Further, since the first and second optically curable materials are cured without heating, the requirement for cure ovens, which were necessary to cure conventional thermally curable materials, is eliminated further minimizing the fabrication cost of the image sensor package.
Also in accordance with one embodiment of the present invention, an image sensor package includes a substrate and an image sensor coupled to the substrate. An interior trace is coupled to the substrate. A bond wire electrically couples a bond pad of the image sensor to the interior trace. An encapsulant encloses the bond wire, the encapsulant being formed of a first optically curable material that has been cured.
The image sensor package further includes a lid. A lid adhesive couples the lid to the substrate, the lid adhesive being formed of a second optically curable material that has been cured.
The present invention is best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.